1. Field of the Invention
The present invention relates to an optical disk device and a rotation control method.
2. Description of the Related Art
In recent years, it has become routine to use an optical disk as a recording medium that records video and audio in a digital format. It is possible to write visible information on a label surface that is a non-recording surface of the optical disk. For example, writing information that pertains to the contents of the optical disk and the like makes it easier to manage the optical disk.
A technology is known that provides a label surface on the optical disk on which information can be printed by an ink jet printer. The printing by the ink jet printer has the advantages that the visible information can be written on the label surface at high speed and can be written in an attractive form. It is possible to print the visible information on the label surface of this sort of optical disk using an ink jet printer that is separate from an information recording device that records information on the recording surface of the optical disk. It is also possible to print the visible information on the label surface of the rotating optical disk using an information recording device that is provided with a printing unit and thus does not require a separate printing device (for example, Japanese Patent Application Publication No. JP-A-2001-291235 and Japanese Patent Application Publication No. JP-A-2005-346778).
In Japanese Patent Application Publication No. JP-A-2001-291235, an optical disk drive device is disclosed that is capable of printing the entire label surface by using a label printing head with a simple configuration that moves reciprocally in the radial direction of the optical disk and has a degree of freedom in only one dimension, utilizing the rotation of the optical disk during one of data recording and playback. In Japanese Patent Application Publication No. JP-A-2005-346778, a disk drive device is disclosed that, in a case where an image will be formed on a label surface of a recording disk, performs label surface print tracking control based on pits that are arrayed as guides to the label surface.
In a case where an ink jet head can move in the radial direction of the optical disk and the printing is performed by causing the optical disk to rotate, as described above in Japanese Patent Application Publication No. JP-A-2001-291235 and Japanese Patent Application Publication No. JP-A-2005-346778, a location exists on the optical disk at which positions where the printing within one revolution of the optical disk starts and ends are adjacent to one another. Thus, in a case where the printing is done by causing the optical disk to rotate, streak-shaped irregularities occur due to overlapping of dots and gaps between dots at the boundary between the printing start position and the printing end position. In order to suppress the occurrence of these streak-shaped irregularities, it is necessary to control the timing of the discharge of the ink droplets with high precision.